The overall objective is to develop more effective sensory aids for hearing-impaired persons through the use of modern signal processing technology. Improved performance of cochlear implants will be investigated through the use of pre-processing to reduce the noise level and to select the portions of the signal to be presented to the impaired ear. Methods for classifying noise in relation to its effect on speech perception will be developed and used for automatic selection of noise reduction techniques and for hearing aid optimization. In addition, procedures for optimizing the electroacoustic behavior of a hearing aid in response to the level and type of background noise will be developed. After development, the signal- processing algorithms will be evaluated according to their effects on speech intelligibility and/or speech quality for typical listening conditions.